interpretation of the role/motiviation of the informant
any speculation about what was going on?
was there a bit of class-envy at work in the plot- it appeared the informant's family was fairly prosperous, while the other boy, whose father and mother worked in a diary, would have not been as wealthy.
or perhaps keeping us in the dark about the 'suspects' (a few kids who like to get high) was a statement, itself, about the misapplication of concerns, surveillance.
my basic interp. of the film was that you had basically good people working thru a creaky infrastructure, and working out from a tradition of the police state.
the captain was, however, presented as a very intelligent, canny person. that was well done, and interesting all in its own right.
personally, i did think the film-makers were a little too unconcerned with pace - but nevertheless, an excellent film and character study.